The invention lies in the field of fluid mechanics and in particular of fluidic measurement of material characteristics of fluids.
On the one hand, the knowledge of flow resistances in channels through which fluid flows and on the other hand, likewise the exact knowledge of the material characteristics of the flowing fluid, thus for example of the liquid or of the gas, which is delivered through the channels, are important for the assessment and design of fluid-mechanical devices. The respective characteristics are basically intrinsic of the material, but individually also dependent on the different constraints such as the temperature or also the flow speed for example (for example with non-Newtonian fluids).
It is particularly with applications in medical technology, when biologically effective fluids and ones, which are subjected to biological processes, are to be delivered, that the respective characteristics of these fluids may continuously change. A particular application of this type is the delivery of the body's own blood which, with regard to its viscosity, is dependent on different physiological processes. Accordingly for example, a pump power, with a pump which is applied for delivering blood, may be adapted to a continuously monitored blood viscosity.
Different methods for measuring the density and/or the viscosity of fluids are known from the state of the art.
Suitable viscometers are for example known from the literature as flow cups, falling body viscometers, measurement agitation drives, and also from the standardisation.
Likewise known are viscosity and density measurement apparatus, which measure the effect of a fluid on an oscillating element which is located in this.
Moreover, a measuring method is known from the U.S. Pat. No. 6,581,476 B1, with which the rotor of a synchronous motor is driven within a fluid and simultaneously the rotational speed and energy consumption are measured for determining the viscosity.
Against the background of the state of the art, it is the object of the present invention to provide a method and a device, by way of which one may measure fluid-mechanical characteristics of a fluid with as little as possible effort, but in a reliable and accurate manner.